JP3873826B2 - Electronic component recognition apparatus and electronic component recognition method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic component recognition apparatus and an electronic component recognition method that are used in an electronic component mounting apparatus and recognize the position and shape of an electronic component.
[0002]
[Prior art]
A line camera is known as an imaging means for performing position recognition of an electronic component by image processing in an electronic component mounting apparatus or the like. In this line camera, pixels that store charges corresponding to the amount of received light are arranged in a line. When an image of the imaging target is formed on the line camera by the optical system, charges corresponding to the image data of the target are stored in each pixel. By sequentially outputting the electric charge of each pixel as an electric signal, a one-dimensional image in the pixel arrangement direction, that is, the main scanning direction can be obtained. Then, desired two-dimensional image data is acquired by juxtaposing a plurality of one-dimensional images obtained while moving the electronic component in the sub-scanning direction orthogonal to the main scanning direction. In the electronic component mounting apparatus, the movement in the sub-scanning direction is performed by horizontally moving the transfer head holding the electronic component to be recognized above the line camera.
[0003]
[Problems to be solved by the invention]
In order to obtain an appropriate image with such a line camera, it is required to keep the relative speed between the recognition target and the line camera in the sub-scan as constant as possible. However, in the electronic component mounting apparatus, the moving speed of the transfer head is not always strictly constant due to various factors such as an error of a feed mechanism such as a ball screw and a control error. The variation in the moving speed in the sub-scanning direction causes the variation in brightness for each one-dimensional image, and the image accuracy is lowered due to this variation. As described above, the conventional electronic component recognition apparatus using a one-dimensional camera such as a CCD line camera has a problem that it is difficult to ensure image accuracy.
[0004]
Therefore, an object of the present invention is to provide an electronic component recognition apparatus and an electronic component recognition method that can ensure image accuracy.
[0005]
[Means for Solving the Problems]
The electronic component recognition apparatus according to claim 1 is an electronic component recognition apparatus that captures and recognizes an image of the electronic component held by the transfer head in the electronic component mounting apparatus, and includes a nozzle that holds the electronic component by suction. A transfer head, a one-dimensional camera having a plurality of pixels arranged in a row, and a moving means for moving the transfer head relative to the one-dimensional camera in a direction orthogonal to the arrangement direction of the pixels An image recognition unit for recognizing the electronic component based on a plurality of one-dimensional images obtained by imaging the electronic component relatively moved by the moving means with the one-dimensional camera, and an imaging area of the one-dimensional camera. An illuminating unit that illuminates a passing electronic component, a light guiding unit that guides illumination light of the illuminating unit to a pixel set as a photometric reference pixel among the plurality of pixels, and an electric power output from the photometric reference pixel And a picture signal correcting means for correcting the image signal output from the pixel excluding the reference pixel for the photometric among the plurality of pixels based on the signal.
[0006]
3. The electronic component recognition method according to claim 2, wherein an image of the electronic component held by the transfer head in the electronic component mounting apparatus is captured and recognized by a one-dimensional camera having a plurality of pixels arranged in a line. A recognition method comprising: a relative movement step of moving a transfer head that sucks and holds an electronic component relative to a one-dimensional camera in a direction perpendicular to the pixel arrangement direction; An image recognition step of recognizing the electronic component based on a plurality of one-dimensional images obtained by imaging with the one-dimensional camera, and in this image recognition step, an electronic component that passes through the imaging area of the one-dimensional camera The illumination light of the illuminating unit that illuminates the light is guided to a pixel set as a photometric reference pixel among the plurality of pixels and is received, and the image correction electrical signal output from the photometric reference pixel is received. Zui by correcting the image signal output from the pixel excluding the reference pixel for the photometric among the plurality of pixels.
[0007]
According to the present invention, in an image recognition process for recognizing an electronic component based on a plurality of one-dimensional images obtained by imaging a moving electronic component with a one-dimensional camera, an electronic device that passes through an imaging area of the one-dimensional camera. The illumination light of the illumination unit that illuminates the component is guided to a pixel set as a photometric reference pixel among a plurality of pixels, and is output from the pixel based on an electrical signal for image correction output from the photometric reference pixel By correcting the image signal that has been corrected, it is possible to appropriately correct image variations caused by variations in relative movement speed.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an electronic component mounting apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of an electronic component recognition apparatus according to an embodiment of the present invention, and FIG. FIG. 3B is an explanatory diagram of the output signal of the line sensor of the electronic component recognition device according to the embodiment of the present invention, and FIG. 4 is a diagram illustrating the configuration of the camera of the electronic component recognition device of the embodiment. The figure which shows the signal output timing of the line sensor of the electronic component recognition apparatus of one Embodiment, FIG. 5 is explanatory drawing of the signal output of the line sensor of the electronic component recognition apparatus of one Embodiment of this invention.
[0009]
First, an electronic component mounting apparatus will be described with reference to FIG. In FIG. 1, a transport path 2 is arranged in the X direction at the center of a base 1. The transport path 2 transports and positions the substrate 3. Component supply units 4 that supply electronic components are disposed on both sides of the conveyance path 2, and a large number of tape feeders 5 are arranged in parallel in each component supply unit 4. The tape feeder 5 stores electronic components held on the tape, and feeds the electronic components to the pickup position by pitch-feeding the tape.
[0010]
Two Y-axis tables 6A and 6B are arranged in parallel at both end portions of the upper surface of the base 1, and an X-axis table 7 on which a transfer head 8 is mounted is installed on the Y-axis tables 6A and 6B. Has been. The transfer head 8 includes a plurality of suction nozzles 8a (FIG. 2) for sucking electronic components at the lower end. By driving the Y-axis tables 6A and 6B and the X-axis table, the transfer head 8 moves horizontally, picks up an electronic component from the pickup position of the tape feeder 5, and transfers and mounts it on the substrate 3.
[0011]
Next, an electronic component recognition apparatus that captures and recognizes an image of an electronic component held by the transfer head 8 in the electronic component mounting apparatus will be described with reference to FIGS. On the movement path of the transfer head 8 between the conveyance path 2 and the component supply unit 4, a camera 9 that reads an image of the electronic component is disposed. The camera 9 is a line camera (one-dimensional camera) and includes a line sensor 11 in which a plurality of pixels having photoelectric conversion elements are arranged in a row in the Y direction. On both sides of the camera 9, illumination units 10 that illuminate electronic components that pass through the imaging area of the camera 9 are arranged.
[0012]
As shown in FIG. 2, with the electronic component P held by the suction nozzle 8a of the transfer head 8 positioned on the camera 9, the illumination unit 10 is turned on to illuminate the electronic component P from below. An optical image of the electronic component P is formed on each pixel of the line sensor 11. An image signal obtained by converting the optical image into an electrical signal is constantly output to the signal capturing unit 12.
[0013]
The X-axis table 7 that moves the transfer head 8 includes a motor 7 a and a feed screw 7 c, and the motor 7 a is controlled by the motor control unit 13. The motor control unit 13 controls the motor 7a in accordance with a speed command and a position command transmitted via the CPU 19, whereby the transfer head 8 moves with respect to the camera 9 in a predetermined movement pattern in the X direction.
[0014]
By taking an image with the camera 9 while moving the transfer head 8, the camera 9 acquires a scanned image of the electronic component P. The X-axis table 7 is configured so that the transfer head 8 holding the electronic component P, which is an imaging object, is relative to the line sensor 11 of the camera 9 in a direction (X direction) orthogonal to the pixel arrangement direction (Y direction). It is a moving means to move. Then, recognition and position detection of the electronic component P are performed by recognizing the obtained scanned image, and when the electronic component P is mounted on the substrate 3, the positional deviation is corrected based on the position detection result. .
[0015]
The motor 7a includes an encoder 7b, and a pulse signal output from the encoder 7b is sent to the motor control unit 13. The pulse detection unit 14 to which this pulse signal is transmitted from the motor control unit 13 detects the position of the transfer head 8 based on this pulse signal, and outputs it to the image capture command unit 15 as the current position.
[0016]
Next, the camera 9 will be described with reference to FIG. The camera 9 has a configuration in which line sensors 11 are arranged in the Y direction below the optical system 9a. Here, among the plurality of pixels 11a (1 to m) of the line sensor 11, the pixel 11a located in the pixel range PX1 (1 to n) for n from the top pixel is set as a photometric reference pixel. A light shielding partition 11b is provided at the boundary with the pixel range PX2 (n + 1 to m) excluding the pixel range PX1.
[0017]
The pixel 11a in the pixel range PX1 receives only the reflected light reflected from the reflector 20 to the optical system 9a among the illumination light emitted from the illumination unit 10 as photometric reference light. The reflection plate 20 serves as a light guide unit that guides the illumination light of the illumination unit 10 to the pixels in the pixel range PX1 set as the photometric reference pixel among the plurality of pixels 11a. As shown in FIG. 3B, the pixel 11a in the pixel range PX1 outputs the charge accumulated by this light reception as a photometric reference signal 21. VA indicates the voltage value of the photometric reference signal 21 output as an analog signal.
[0018]
The pixel range PX2 excluding the pixel range PX1 is an image signal capturing range for imaging the electronic component P, and these pixels 11a receive the reflected light from the electronic component P, as shown in FIG. As shown, the charge accumulated by the light reception is output as an image signal 22 including an image to be imaged. VB indicates the voltage value of the image signal 22 output as an analog signal. Note that the pixel range PX1 as the photometric reference pixel is set to an unnecessary pixel range excluding a range required for imaging the electronic component P.
[0019]
In FIG. 2, the signal capturing unit 12 connected to the line sensor 11 includes an image signal capturing unit 12a and a reference signal capturing unit 12b. The image signal capture unit 12a captures an image signal output from the pixel 11a in the pixel range PX2 among the pixels of the line sensor 11, and the reference signal capture unit 12b performs photometry output from the pixel 11a in the pixel range PX1. For reference signal.
[0020]
The signal capture from the line sensor 11 is performed when the signal capture unit 12 receives the image capture command signal output from the image capture command unit 15. That is, the pulse detection unit 14 receives and counts a pulse signal transmitted from the encoder 7b of the motor 7a that drives the transfer head 8 in the X direction, and the count value becomes a count value corresponding to a specific position of the transfer head 8. At the timing of arrival, an image capture command signal is output to the signal capture unit 12.
[0021]
Then, using this image capture command signal as a trigger, the charges accumulated in the pixels at each scanning time are output as electrical signals in order from the top pixel of the line sensor 11. At this time, as described above, the signal output from the n pixels (pixel range PX1) from the top is captured by the reference signal capturing unit 12b and output from the subsequent pixels (pixel range PX2). Is captured by the image signal capturing unit 12a.
[0022]
The reference signal capture unit 12b and the image signal capture unit 12a are connected to the image correction reference value setting unit 16 and the image correction unit 17, respectively. The image correction reference value setting unit 16 and the image correction unit 17 include The photometric reference signal 21 (voltage value VA) and the image signal 22 (voltage value VB) shown in FIG.
[0023]
When receiving the photometric reference signal 21, the image correction reference value setting unit 16 samples and holds a representative voltage value [VA] close to the average value of the voltage value VA. The image correction unit 17 uses the voltage value [VA]. Communicate against. The voltage value [VA] is used as a reference value for image signal correction in the image correction unit 17 as will be described later. As the voltage value [VA], a voltage value corresponding to the amount of charge accumulated in a pixel located substantially in the center of the pixel range PX1 may be sampled and held, and the charge amount of all the pixels in the pixel range PX1 may be sampled and held. An average value may be used.
[0024]
The image correction unit 17 outputs a digitized one-dimensional image signal to the image recognition unit 18 by performing A / D conversion on the image signal 22 that is an analog electrical signal received from the image signal capturing unit 12a. To do. Then, the image recognition unit 18 acquires a two-dimensional image of the recognition-target electronic component P from a plurality of one-dimensional images obtained by sequentially imaging the recognition-target electronic component P that moves relative to the camera 9, The electronic component P is recognized based on the two-dimensional image.
[0025]
Next, image signal correction processing performed when the image correction unit 17 performs A / D conversion of the image signal will be described with reference to FIGS. 4 and 5. FIG. 4A shows a pulse p1 that is detected by the pulse detector 14 as the timing of signal capture from the line sensor 11 out of the pulse signal transmitted from the encoder 7b of the motor 7a and output to the image capture command unit 15. , P2, p3...
[0026]
FIG. 4B shows image data D1, D2, D3... Output from the line sensor 11 for each scanning time in synchronization with these pulse signals. That is, the image data D1 obtained by exposing the line sensor 11 between the pulses p1 and p2 is output using the pulse P2 as a trigger, and the image data D2 obtained by exposing the line sensor 11 between the pulses p2 and p3. Is output with the pulse P3 as a trigger.
[0027]
At this time, as shown in FIG. 4A, intervals T1, T2,... Indicating intervals between the pulses are not always constant, and errors and control errors of the feed screw 7c constituting the moving means of the transfer head 8 In many cases, it varies depending on various factors. When the pulse interval varies, the exposure times t1 and t2 of the line sensor 11 become longer and shorter, and the amount of charge accumulated in each pixel is different during this time, so that the output image signals D1 and D2 have different strengths. That is, even when the light receiving amount should be equal to the original, the brightness of the one-dimensional image obtained by the variation in the relative moving speed of the transfer head 8 is different, and the image accuracy is lowered.
[0028]
In order to prevent such a reduction in image accuracy, in the electronic component recognition apparatus of the present embodiment, when the image correction unit 17 performs A / D conversion of the image signal, a representative voltage value of the photometric reference signal [ VA], the voltage value VB of the image signal 22 is corrected. That is, the voltage value VC of the digital image signal output from the image correction unit 17 to the image recognition unit 18 is not the voltage value VB transmitted from the image signal capturing unit 12a but VC = VB / [VA]. The voltage value converted by the conversion formula is output. Therefore, the image correction reference value setting unit 16 and the image correction unit 17 serve as image signal correction means for correcting the image signal output from the pixel of the line sensor 11 based on the electrical signal output from the photometric reference pixel. ing.
[0029]
This conversion process will be described with reference to FIG. 5 for an example of the image data D1 and D2 shown in FIG. FIGS. 5A and 5C show the photometric reference signal 21 and the image signal 22 captured by the signal capturing unit 12 for each of the image signals D1 and D2. 5B and 5D are image signals output based on the photometric reference signal 21 and the image signal 22, that is, VC1 = VB1 / [VA1] and VC2 = VB2 / [VA2]. An image signal output after being converted is shown.
[0030]
Here, since the photometric reference signal 21 and the image signal 22 are both electrical signals based on the amount of charge exposed in a common exposure time, the voltage value VB and the voltage value [VA] are in a proportional relationship. is there. Therefore, by obtaining a value obtained by dividing VB by [VA] as the image signal VC, it is possible to obtain an image signal having a voltage value VC in which the influence due to variations in exposure time is eliminated.
[0031]
That is, in the image recognition method by the electronic component recognition apparatus, the transfer head 8 holding the electronic component P is moved relative to the camera 9 in a direction orthogonal to the pixel arrangement direction of the line sensor 11 ( Relative movement step), the electronic component P is recognized based on a plurality of one-dimensional images obtained by imaging the electronic component P in relative movement with the camera 9 (image recognition step). In this image recognition process, the illumination light of the illumination unit 10 that illuminates the electronic component P that passes through the imaging area of the camera 9 is guided to and received by the pixel 11a set as the photometric reference pixel among the plurality of pixels 11a. The image signal output from the pixel is corrected based on the electric signal for image correction output from the pixel 11a.
[0032]
In a two-dimensional image obtained by arranging such one-dimensional images in parallel, there is no light / dark variation due to variations in relative movement speed between the camera 9 and the imaging target. Can be performed with high accuracy. Since the image signal 22 is corrected using the photometric reference signal 21 obtained from the same illumination, the variation in the image due to the change in the brightness of the illumination unit 10 over time is appropriately corrected, and high Accurate image recognition can be performed.
[0033]
【The invention's effect】
According to the present invention, in an image recognition process for recognizing an electronic component based on a plurality of one-dimensional images obtained by imaging a moving electronic component with a one-dimensional camera, an electronic device that passes through an imaging area of the one-dimensional camera. The illumination light of the illumination unit that illuminates the component is guided to a pixel set as a photometric reference pixel among a plurality of pixels, and is output from the pixel based on an electrical signal for image correction output from the photometric reference pixel Since the corrected image signal is corrected, it is possible to perform high-accuracy image recognition that appropriately corrects image variations caused by variations in relative movement speed and eliminates errors on images that do not exist originally. .
[Brief description of the drawings]
FIG. 1 is a perspective view of an electronic component mounting apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of an electronic component recognition apparatus according to an embodiment of the present invention. FIG. 4B is an explanatory diagram of the configuration of the camera of the electronic component recognition apparatus according to the embodiment of the present invention. FIG. 4B is an explanatory diagram of the output signal of the line sensor of the electronic component recognition apparatus according to the embodiment of the present invention. The figure which shows the signal output timing of the line sensor of the electronic component recognition apparatus of form. FIG. 5 is explanatory drawing of the signal output of the line sensor of the electronic component recognition apparatus of one embodiment of this invention.
7 X-axis table 8 Transfer head 9 Camera 10 Illumination unit 11 Line sensor 11a Pixel 12 Signal acquisition unit 16 Image correction reference value setting unit 17 Image correction unit 18 Image recognition unit

Claims (2)

An electronic component recognition apparatus for capturing and recognizing an image of an electronic component held by a transfer head in an electronic component mounting apparatus, the transfer head having a nozzle for sucking and holding the electronic component, and arranged in a row A one-dimensional camera having a plurality of pixels, a moving means for moving the transfer head relative to the one-dimensional camera in a direction orthogonal to the arrangement direction of the pixels, and an electronic component relatively moved by the moving means An image recognition unit that recognizes the electronic component based on a plurality of one-dimensional images obtained by imaging with the one-dimensional camera, an illumination unit that illuminates the electronic component that passes through the imaging area of the one-dimensional camera, and guiding means for guiding the illumination light of the illumination portion on the pixels set as the reference pixel photometric among the plurality of pixels, the plurality of pixels based on the electrical signal output from the reference pixel photometry Electronic component recognition apparatus characterized by comprising an image signal correcting means for correcting the image signal output from the pixel excluding the reference pixel for the metering. An electronic component recognition method for capturing and recognizing an image of an electronic component held on a transfer head in an electronic component mounting apparatus by a one-dimensional camera having a plurality of pixels arranged in a row, and holding the electronic component by suction And a relative movement step of moving the transfer head relative to the one-dimensional camera in a direction orthogonal to the pixel arrangement direction, and the one-dimensional camera picked up an image of the electronic component during the relative movement. An image recognition step of recognizing the electronic component based on a plurality of one-dimensional images, and in the image recognition step, the illumination light of an illuminating unit that illuminates the electronic component passing through the imaging area of the one-dimensional camera is received guided to pixels set as the reference pixel for metering of the pixel, the measurement of the plurality of pixels based on the electric signal for image correction output from the reference pixel photometry Electronic component recognizing method and correcting an image signal output from the pixel excluding the use reference pixels.

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